FIELD OF THE INVENTION
In the exploded view of FIG. 1 it is possible to see the construction of a shaft seal for the output end of a crankshaft of a motor vehicle, such as is used at present according to the prior art.
The essential parts of this crankshaft seal are a radial shaft seal ring 1, a gasket receptacle 2 in the form of an aluminium pressure die casting 20 with a passage opening 21 for a crankshaft 7, a flat gasket 3 for sealing the gasket receptacle 2 with respect to the end wall 62 of the crankcase 6, an oil pan or sump 8 with a gasket 5, which projects over the end wall 62 of the crankcase 6, so that an underface 27 of the gasket receptacle 2 can sealingly engage against the same.
The manufacture of such a shaft seal requires four working steps:
pressing the raial shaft seal ring 1 into the gasket receptacle 2, PA1 assembly of the flat gasket 3, PA1 application of a pasty sealant between the end face of the flat gasket 3 and the oil sump gasket 5, PA1 assembly of the gasket receptacle 2 with the preassembled radial shaft seal ring 1 on the end face 62 of the engine block 6 by screwing. PA1 damage during packing, transportation, unpacking and preassembly, PA1 tilting during pressing in, PA1 confusion with respect to the fitting position (spring-loaded sealing lip pointing outwards instead of inwards), PA1 leaks on the external diameter; PA1 damage in the bore into which the radial shaft seal ring is pressed, PA1 damage, e.g. scratches, on the sealing face to the flat gasket 3, PA1 damage, e.g. scratches on the sealing face 26 to the oil sump gasket 5, PA1 opening of pores during the machining of the gasket receptacle 2; PA1 damage during packing, transportation, unpacking and preassembly, PA1 dimensional tolerances, PA1 the pasty sealant between the end face of the flat gasket 3 and the oil sump gasket 5 (necessary for tolerance compensation purposes) can either be forgotten or incorrectly applied.
Such a multipart solution leads to numerous fault and error possibilities with respect to the:
Radial shaft seal ring 1:
Gasket receptacle 2:
Flat gasket 3:
DE 36 34 735 C2 discloses a crankshaft seal, in which a shaft seal ring and a static gasket are moulded onto a gasket receptacle in the form of a cup-shaped sheet metal body. For this purpose grooves and connecting channels are provided in the sheet metal body between the dynamic shaft seal ring and the static gasket and through them the elastomeric material flows during moulding from the mould cavity for one gasket to that of the other gasket.
During such a moulding process there is a non-uniform pressure build-up during the filling of the mould cavity for the sealing lip of the dynamic shaft seal ring at the overflow channel to the static gasket, so that it is not possible to ensure the absolutely faultless construction in the vicinity of the sealing edge which is indispensable for satisfactory operation.
EP 139 503 B1 discloses a shaft seal, in which a shaft seal ring and a static gasket are separately shaped onto a gasket receptacle and then the latter forms together with the moulded gaskets a replaceable unit. In this construction the static gasket only provides a seal to the end face of the crankcase and not to the oil sump.
The problem of the invention is to provide a method for the manufacture of a shaft gasket, which is as far as possible based on the proven construction according to FIG. 1, where manufacture has the same process reliability, but assembly is more reliable and less expensive, also with a view to minimum machining of the casting forming the gasket receptacle. This problem is solved by a method according to the present invention.